I am making a small 9V battery powered synthesizer with a square wave oscillator built around a 40106b Schmitt trigger (reference: http://richdecibels.com/blog/?p=11) and a few other components, one of which is a white noise generator (similar to this build: https://www.flickr.com/photos/secondhandsynth/4501573713/)
My problem is, the square wave oscillator is bleeding into every part of the circuit. It's really loud, and its leaking into other sound generators on the circuit board that it's not even connected to in any way besides power and ground. As I probe the circuit board with a speaker input, I can hear the oscillator ring through every part of the build.
Is there a way to isolate a loud oscillator from the rest of the circuit? Or prevent signals from cross-talking on a common ground?